/Engine/Plugins/Importers/USDImporter/Source/USDSchemas/Public/USDInfoCache.h
Provides the total vertex or material slots counts for each primandits subtree. This is built inside RebuildCacheForSubtree, so it will factor in the used Context's bMergeIdenticalMaterialSlots. Note that these aren't affected by actual collapsing: A prim that doesn't collapse its children will still provide the total sum of vertex counts of its entire subtree when queried
[TOptional](API\Runtime\Core\IO\TOptional)< uint64 > GetSubtreeVertexCount ( const [UE::FSdfPath](API\Plugins\UnrealUSDWrapper\UsdWrappers\FSdfPath) & Path )